Understanding the Doppler Effect
The Doppler effect describes the change in frequency of a wave (like sound) as the source of the wave moves relative to an observer. When the source is moving towards the observer, the frequency appears higher (a higher pitch), and when the source is moving away, the frequency appears lower (a lower pitch).
Formula
The formula for the Doppler effect with a moving source is:
```
f' = f * (v_sound / (v_sound - v_source))
```
Where:
* f' is the observed frequency
* f is the source frequency
* v_sound is the speed of sound
* v_source is the speed of the source (the fly)
Calculations
1. Identify the known values:
* f (source frequency) = 162 Hz
* v_sound (speed of sound) = 334 m/s
* v_source (speed of the fly) = 6 m/s
2. Plug the values into the formula:
* f' = 162 Hz * (334 m/s / (334 m/s - 6 m/s))
3. Calculate the observed frequency:
* f' ≈ 164.9 Hz
Answer
The observed hum of the fly as it approaches you would be approximately 164.9 Hz. This is slightly higher than the actual frequency of the fly's wings due to the Doppler effect.
